Mailbox.org cal/contacts not syncing - certificate error?

I’m trying to get mailbox.org setup but I keep getting the following errors (System.Security.Authentication.AuthenticationException: The remote certificate was rejected by the provided RemoteCertificateValidationCallback.).

8:48:33 AM my@email.address [CalDAV] MailClient.Accounts.ConnectionException: An error occurred while sending the request.
—> System.Net.Http.HttpRequestException: An error occurred while sending the request.
—> System.IO.IOException: The read operation failed, see inner exception.
—> System.Security.Authentication.AuthenticationException: The remote certificate was rejected by the provided RemoteCertificateValidationCallback.
at System.Net.Security.SslStream.SendAuthResetSignal(ProtocolToken message, ExceptionDispatchInfo exception)
at System.Net.Security.SslStream.ForceAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Boolean receiveFirst, Byte[] reAuthenticationData, Boolean isApm)
at System.Net.Security.SslStream.ReplyOnReAuthenticationAsync[TIOAdapter](TIOAdapter adapter, Byte[] buffer)
at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory1 buffer) --- End of inner exception stack trace --- at System.Net.Security.SslStream.ReadAsyncInternal[TIOAdapter](TIOAdapter adapter, Memory1 buffer)
at System.Net.Http.HttpConnection.FillAsync(Boolean async)
at System.Net.Http.HttpConnection.ReadNextResponseHeaderLineAsync(Boolean async, Boolean foldedHeadersAllowed)
at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
— End of inner exception stack trace —
at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.AuthenticationHelper.SendWithNtAuthAsync(HttpRequestMessage request, Uri authUri, Boolean async, ICredentials credentials, Boolean isProxyAuth, HttpConnection connection, HttpConnectionPool connectionPool, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.AuthenticationHelper.SendWithAuthAsync(HttpRequestMessage request, Uri authUri, Boolean async, ICredentials credentials, Boolean preAuthenticate, Boolean isProxyAuth, Boolean doRequestAuth, HttpConnectionPool pool, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.DecompressionHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at MailClient.Protocols.InteractionController.CerificationValidationMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
— End of inner exception stack trace —
at MailClient.Protocols.CalDav.ProtocolCommands.Connector.RunCommand(CalDavAccount account, ICommand command, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.FolderSynchronizer.UpdateOptions(Uri[] baseUris, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.FolderSynchronizer.Bootstrap(WorkerStatus status, CancellationToken cancellationToken)
at MailClient.Protocols.CalDav.CalDavGenericCommand.Execute(WorkerStatus status)
at MailClient.Commands.Command.Process(WorkerStatus status)
EnqueuedStackTrace =
at MailClient.Protocols.CalDav.FolderSynchronizer.GoOnlinePre()
at MailClient.Protocols.CalDav.CalDavAccount.GoOnlineInt()
at MailClient.Protocols.Common.AccountBase.ChangeOnlineState(Boolean online, OfflineReason offlineReason)
at MailClient.Protocols.Common.AccountBase.GoOnline()
at MailClient.Protocols.Common.AccountBase.RunIfOnline(Action actionIfOnline, Action actionIfOffline)
at MailClient.Protocols.CalDav.CalDavAccount.Synchronize(SynchronizationPriority priority)
at MailClient.Accounts.BindingAccountBase.Receive()
at MailClient.Accounts.AccountManager.ReceiveAllInternal()
at MailClient.Accounts.AccountManager.SendAndReceiveAll()
at MailClient.Accounts.AccountManager.timerSendAndReceive_Tick(Object sender, EventArgs e)
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)
at Interop.User32.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.Interop.Mso.IMsoComponentManager.FPushMessageLoop(UIntPtr dwComponentID, msoloop uReason, Void* pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(msoloop reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(msoloop reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(ApplicationContext context)
at MailClient.Program.<>c.b__173_1()
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Delegate.DynamicInvokeImpl(Object[] args)
at System.Delegate.DynamicInvoke(Object[] args)
at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)
at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)
at System.Windows.Forms.Control.InvokeMarshaledCallbacks()
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at MailClient.Common.UI.Forms.BaseForm.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)
at Xilium.CefGlue.Interop.libcef.run_message_loop()
at MailClient.Program.Main(String[] args)
GUIStatus_Exception_Reported = True

Is this with a Windows Insider or Windows 11?

If so, it currently does not support CalDAV syncing.

It is, let me know if you need any help testing.

You will need to ask Microsoft about that. :wink:

I guess because it was just released as a preview, they still have a of of work to do before it is officially released at the end of the year. Until they resolve it, you will not be able to use CalDAV.

Yep probably still lots of bugs in Windows 11, and from what i’ve read it won’t be officially released till round Oct sometime. Probably best to stick to Win 10 for now.

I don’t think Windows 11 is the problem…right now, I’m using Outlook with no problem syncing with Caldav/Carddav…I’m interested to move to eM client but caldav is a must have.

Any update here?

Thanks!!

With the beta version of Windows 11 (and some Insider releases of Windows 10), eM Client will not be able to sync CalDAV.

This has to do with TLS 1.3 being enabled by default, and .NET.

It is not the same with MS Outlook, as is not using .NET.

Unfortunately, you will need to wait for the official release of the OS, or contact me directly (gary@emclient.com) if you are interested in testing an internal version that has a temporary fix until the OS is released.

1 Like

I am on Windows 11 Insider Beta Channel - Windows 11 Pro, 21H2, Build 22000.184.
eM Client ( https://licensemanager.emclient.com - Profile “Test”) on Version 8.2.1533.
No Problems with mailbox.org E-Mail / CalDAV / CardDAV here.

@DietmarR, yes, that version also has the WIndows 11 workaround.

Windows 11 users can download and install the latest version in the Release History.

This will work with Windows 11.